This invention is directed to a transducer for a quartz crystal timepiece and in particular to a two pole step motor for use in a quartz cystal timepiece.
Heretofore, conventional step motors utilized in electronic timepieces have taken on various forms. One widely used step motor includes a pair of stators surrounding a rotor having six poles. Nevertheless, the effective torque of the rotor is determined by only two of the magnetic poles, thereby rendering the remaining pole unnecessary, and further resulting in a reduction in the efficiency of the step motor. Moreover, although the use of six rotor poles is designed to effect a rotation of the rotor through an angle of 60.degree. in response to each pulse applied to the motor, quite often the rotor is rotated through an angle of 120.degree. in response to a single pulse due to the inertia caused by the rotation thereof. Additionally, magnetization of the rotor in such manner as to provide six poles of equal magnetization force, is both expensive and difficult to effect.
In order to overcome these difficulties, step motors wherein a permanent magnet rotor is disposed directly inside a solenoid have been utilized. Nevertheless, in such motors, the cavity magnetic field generated by the solenoid is directly utilized to effect rotation of the rotor, and accordingly, it is difficult to concentrate the magnetic flux in such motor arrangements, thereby resulting in low efficiency. Accordingly, like the above noted arrangement, considerable current is required to generate sufficient power to effect a rotation of the rotor, a less than completely satisfactory feature in electronic timepieces wherein minimum current extends the life of the battery utilized to effect energization of such timepiece circuitry.